Screw type closure cap

ABSTRACT

THE SCREW TYPE CLOSURE CAP INCLUDES A FIRST CAP FOR DIRECTLY SEALING A CONTAINER OPENING HAVING INTERNAL ENGAGEMENT MEANS FOR ENGAGING CLOSURE RETAINING MEANS ON THE CONTAINER. THE INTERNAL ENGAGEMENT MEANS IS FORMED TO PERMIT LIMITED LONGITUDINAL MOVEMENT OF THE FIRST CAP RELATIVE TO THE CLOSURE RETAINING MEANS AFTER ENGAGEMENT THEREWITH. AN OVERCAP IS FORMED TO OVERLIE SAID FIRST CAP AND APPLY PRESSURE THERETO TO MOVE SAID FIRST CAP LONGITUDINALLY AND INCREASE THE SEALING PRESSURE THEREOF AGAINST THE OPEN END OF THE CONTAINER.

May 23, 1972 B. E. EMERY 3,664,536

SCREW TYPE CLOSURE CAP Filed May 22, 1970 2 Sheets-Sheet l :iii jjjij 24ll 26 "-i" INVENTOR. BYRO/V E. EMERY BY QM (My ATTORNEYS May 23,1972 B.E. EMERY SCREW TYPE CLOSURE CAP 2 Sheets-Sheet 2 Filed May 22, 1970INVENTOR. BymnEE/nery BY 19 U) United States Patent O 3,664,536 SCREWTYPE CLOSURE CAP Byron E. Emery, El Cerrito, Calif., assignor to CutterLaboratories, Inc., Berkeley, Calif. Filed May 22, 1970, Ser. No. 39,611Int. Cl. B65d 23/00, 53/00 U.S. Cl. 21540 11 Claims ABSTRACT OF THEDISCLOSURE BACKGROUND OF THE INVENTION The present invention relates toan improved screw type closure cap adapted to provide an effectivesealing closure for the open end of a bottle or container and which maybe easily removed therefrom.

For many applications, it is imperative that a bottle or other containerbe completely sealed to preclude any leakage of the contents. Such aseal is particularly essential when the contents of the containerconstitute a gas or a liquid containing gas. Likewise, a good seal isessential when the inward or outward pressure on the con tainer mightvary significantly, such as would occur if it is necessary to heatsterilize the container and contents. A conventional method for sealingsuch containers is to employ a screw cap for the container which createsa seal by compressing resilient rubber or similar elastomeric materialagainst the end of the container. The sealing pressure pre-set upon thescrew cap is maintained by the holding force of the screw cap on thethreads of the container. The problem presented by a screw cap of thistype is that a balance must be established between the downward pressureor force required for an effective seal and the torque required tounscrew the cap from the container. In many cases, to facilitate removalof the cap, pressure required for an effective seal is sacrificed.

Also, if the container constitutes a glass bottle, a specialized machinemust be employed to obtain a smooth top surface on the bottle neck forsealing purposes. Regular blowing machines used in the production ofbottles adapted to receive a plug stopper do not produce a top sealingsurface of sufficient smoothness to provide a good seal withconventional screw caps at pressures which permit manual removal of thecap.

In an attempt to provide an effective sealing cap while facilitating capremoval from a sealed container, tamperproof caps have been developedwhich include a screw cap having an integral sealing skirt formed by atear strip which is operable to break the seal of the container. Oncethe tear strip is removed, air is permitted to freely enter thecontainer under the screw cap to remove frictional forces whichcounteract cap removal.

Such sealing caps require the provision of auxiliary gaskets on the tearstrip to produce a seal against the side of the container. Not only areeffective side seals difficult to achieve due to the necessity forproviding high sealing forces against the side of a container with athin tear strip, but also rupture of the tear strip completely destroysthe sealing capability of the cap.

It is a primary object of the present invention to provide 3,664,536Patented May 23, 1972 a novel and improved screw type closure cap whichis adapted to provide a high sealing pressure against a supportingcontainer but which may be easily removed from the container by themanual application of a low removal torque.

Another object of the present invention is to provide a novel andimproved screw type closure cap which will provide an effective seal forglass bottles formed by conventional blowing machines which may includeslight irregularities in the cap engaging surfaces.

A further object of the present invention is to provide a novel andimproved screw type closure cap which is rendered tamper proof by anovercap applied to a screw threaded sealing cap; such overcapattributing a high sealing pressure to the sealing cap.

Another object of the present invention is to provide a novel andimproved screw type closure cap which includes an overcap applied to ascrew threaded sealing cap to increase the sealing pressure of thesealing cap; the normal sealing capabilities of the sealing cap beingretained upon destruction of the overcap.

A still further object of the present invention is to provide a novelmethod for forming a screw type sealing cap by applying a first cap to acontainer at a first pressure and subsequently forming threads thereinto engage the container and then applying a second cap to the first capat a second higher pressure and subsequently engaging the second cap tothe container.

These and other objects of the present invention will become readilyapparent upon consideration of the following specification and claimstaken in conjunction with the accompanying drawing in which:

FIG. 1 is an exploded sectional view of the screw type closure cap;

FIG. 2 is a sectional view illustrating the sealing cap portion of thescrew type closure cap in place on a container;

FIG. 3 is a sectional view illustrating the screw type closure cap inplace on a container; and

FIG. 4 is a sectional view of an embodiment of the overcap for the screwtype closure cap.

Referring to the drawing, the screw type closure cap of the presentinvention indicated generally at 10 includes a sealing cap 12 adapted toclose the open end of a container 14. For purposes of description, thecontainer 14 is illustrated as a glass bottle of conventionalconstruction having a neck 16 provided with external screw threads 18which extend from a point adjacent the bottle opening to an enlargedsealing ring 20. It is apparent that other containers having capengaging means equivalent to the external screw threads and sealing ringmay be employed with the screw type closure cap 10.

The sealing cap 12 includes a top closure wall 22 with a cylindricalskirt 24 depending therefrom. The skirt 24 is formed with internal screwthreads 26 which are adapted to engage the external threads 18 on thebottle 14. Thus the sealing cap is operable in the same manner asconventional screw type bottle caps, and upon rotation of the sealingcap, the threads 26 may be engaged with the threads 18 to draw thesealing cap down over the open end of the bottle until the lower portionof the skirt 24 contacts the sealing ring 20.

A sealing disc 28 of rubber, plastic, or similar material may be adaptedto fit within the sealing cap to form a seal between the sealing cap andthe top edge of the bottle neck 14. Also, a metallic disc 30 of aluminumor similar metal may be provided to separate the sealing disc from thetop closure wall 22 of the sealing cap. Both the sealing disc andmetallic disc are formed to a diameter which is greater than thediameter of the bottle neck so that these discs extend laterally beyondthe confines of the bottle neck when the sealing cap is engagedtherewith. In

many containers, such as drink and food containers, the separate sealingand metallic discs 28 and 30 may be omitted and replaced by a layer ofelastomeric material bonded to the top closure wall 22 of the sealingcap.

As illustrated in FIG. 2, the sealing cap may be threaded onto the neckof the bottle 14 unil the top closure wall 22 thereof compresses thesealing disc 28 to provide a sealing closure for the open end of thebottle. In this manner, the sealing cap operates as a conventionalbottle cap. However, it will be noted in FIG. 2 that the internalthreads 26 of the sealing cap do not fill the spaces between theexternal bottle threads 18. Instead, the internal threads 26 contactonly the underside of the external threads 18, and the bottom of eachinternal thread is spaced above the top of the next suceeding externalthread.

The sealing cap 12 is removably secured to the bottle 14 so as to exertsealing pressure downwardly against the sealing disc 28. This sealingpressure is limited to a value which will permit easy manual removal ofthe sealing cap from the bottle.

To increase the effective sealing pressure of the sealing cap 12, anovercap 32 is provided. This overcap includes a top wall 34 adapted toengage the top wall 22 of the sealing cap and a depending skirt portion36. The lower periphery of the skirt portion 36 is provided with anindented rim 38 which extends under the sealing ring to lock the overcaponto the bottle 14.

This indented rim portion may be part of a tear away section or the rimportion might be of rolled metal similar to that used in bottle capswhere an opener is employed to snap the rim over the sealing ring toremove the cap. Also, the overcap may incorporate design features whichmake the use of screw threads feasible to retain the overcap on thecontainer neck as will subsequently be described in connection with FIG.4.

The overcap 32 may be constructed to provide a tamper proof protectivecap for the sealing cap 12, and in this form, the overcap constitutes atear away cap which must be torn from the bottle before the sealing capcan be removed. The overcap may be formed of metal foil material whichis adapted to be torn or of stronger metal, plastic or similar materialhaving a weakened rupture line or tear strip. For example, the juncture39 between the indented rim 38 and the skirt portion 36 may be weakenedso that the indented rim may be severed from the skirt portion to permitremoval of the overcap.

The overcap 32 is engaged with the bottle 14 in a manner which causesthe overcap to exert a downward pressure on the sealing cap 12 which isgreater than the pressure previously applied by the sealing cap to thesealing disc 28. Thus, with the overcap in place as illustrated in FIG.3, the sealing cap is moved downwardly to increase the sealing pressurebetween the sealing disc and the upper edge of the bottle neck. Themetallic disc 30 applies force across the top surface of the sealingdisc, thereby causing the sealing disc to overhang the neck of thebottle 14 and to engage the sides thereof adjacent the bottle opening.This added side seal is effective when the edge of the bottle adjacentto the opening is irregular.

It will be noted that with the overcap in place, the internal threads 26of the sealing cap are moved downwardly away from engagement with theunderside of the external threads 18 on the bottle neck so thatsubstantially all contact between the internal threads and the externalthreads is eliminated. The internal threads are formed so that whencontact with the bottom of an external thread is broken, there is stillspace between the bottom of an internal thread and the next succeedingexternal thread. Thus with the overcap in place, the internal threadsare somewhat free floating and substantially no pressure exists betweenthese threads and the bottle neck 14. This provides limited compensationfor internal pressure variations within the bottle.

If only the sealing cap 12 were to provide the increased sealingpressure added by the overcap 32, it would be difficult to manuallyremove the sealing cap from the bottle 14. However, when the overcap isremoved, the sealing cap again returns to the position of light sealillustrated in FIG. 2, and may be easily removed manually. It isimportant to note that removal of the overcap does not destroy the sealprovided by the sealing cap.

The increased pressure provided by the overcap 32 positively eliminatesthe incidence of container leakage occurring when the lower sealingpressure necessary for the manual removal of the conventional screw sealcaps is employed. Additionally, use of the screw type closure cap 10makes it unnecessary to employ special machinery to form the sealingsurface at the top of a glass bottle neck, and regular blowing machinesmay be used.

In accordance with the method of the present invention, the screw typeclosure cap 10 is formed by placing a threadless cap blank for thesealing cap 12 with the sealing disc 28 and metal disc 30 in place, overthe end of the bottle neck 16. A first downward force is then applied tothe top closure wall 22 of the cap blank to compress the sealing disc,such first force being limited to a value which will facilitatesubsequent manual removal of the finished sealing cap. For purposes ofdescription, a force of 25 lbs. will be employed.

With a 25 lb. force on the sealing cap blank, the internal threads 26are rolled into the sealing cap blank to mate with the external threads18 on the bottle 14. To obtain the proper spacing of the internalthreads between the external threads, the internal threads may be rolledto be smaller in radius than the clearance of the external threads onthe bottle, or the relative pitch of the internal and external threadsmay be varied to provide the desired spacing. It will be noted in FIG. 2that the internal threads 26 extend inwardly beyond the outer confinesof the dealing disc 28 and metallic disc 30 so that these discs areretained within the sealing cap by the internal threads when the sealingcap is removed from the bottle. In some cases, it is desirable to form aseal retaining projection 26a during the formation of the internalthreads to engage and positively retain the sealing disc.

After the sealing cap 12 is secured to the bottle 14, an overcap blankwithout the rim 38 is placed over the sealing cap and a second downwardforce of greater magnitude than the first force previously applied tothe sealing cap blank is applied to the top wall 34 thereof. Fordescriptive purposes only, the second force will be denoted as lbs.

The second force further compresses the sealing disc 28 to provide afinal seal, and once this seal is established, the rim 38 is rolled intothe overcap blank to mate the overcap with the sealing ring 20.

Referring now to FIG. 4 an embodiment of the overcap 32 of FIGS. 13 isillustrated. This overcap, indicated at 40, is designed for use withcontainers having external threads 18 which extend down the container orbottle neck beyond the sealing ring 20 in FIGS. l-3. As the bottle necktapers outwardly, the external threads in this area extend laterallybeyond the external threads adjacent the bottle opening, and thereforethese threads may receive the overcap 40 as the overcap is fit over thesealing cap 12.

The overcap 40 includes a top Wall 42 and a depending skirt portion 44.The lower section of this skirt portion is formed with internal screwthreads 46 which are adapted to engage the external threads 18 on thebottle 14 below the lowermost extremity of the sealing cap when thesealing cap is in place on the bottle.

The top wall 42 of the overcap 40 is formed to minimize the frictionalcontact between the overcap and the sealing cap 12. Thus cap seats 48are provided on the internal surface of the overcap top wall to engagethe top wall 22 of the sealing cap. These cap seats may be formed byscoring, punching, or otherwise indenting the top wall 42 to provideprojecting cap seats of minimal contact area. Thus, when the overcap 40is threaded onto the externl threads 18 over the sealing cap 12 to exertan increased downward pressure on the sealing disc 28, only the capseats 48 will contact the top Wall of the sealing cap. This minimalcontact permits the overcap to be manually removed with ease, asfrictional contact with the sealing cap has been minimized.

It will be apparent that the present invention provides a noveltamper-proof screw type cap which is adapted for use on a wide varietyof containers. This cap greatly enhances the normal sealing ability of athreaded sealing cap while maintaining the sealing capability of suchsealing cap when the overcap is removed.

I claim:

1. A sealing closure for the open end of the neck portion of acontainer, said neck portion being provided with external closureretaining means, comprising:

a first cap (12) for closing the container opening, said first caphaving a first top wall portion (22) adjacent the extremity of saidcontainer open end, and a first cylindrical skirt portion (24) arrangedconcentrically about said container open end;

a layer of resilient sealing material (28) arranged Within said firstcap adjacent said top closure wall portion for engaging and sealing theopen end of said container;

internal engagement means (26) carried by the lower end of the skirtportion of said first cap for engaging said container external closureretainer means to progressively compress said layer of resilient sealingmaterial to a desired first degree of compression, said internalengagement means being formed to permit limited longitudinal movement ofsaid first cap relative to said external closure retaining means afterengagement therewith;

overcap means (32) adapted to overlie said first cap, said overcap meansincluding a second top wall portion (34) arranged above and parallelwith said first top wall portion, and a second cylindrical skirt portion(36) arranged concentrically about said first skirt portion; and

connecting means (38, 46) for connecting said overcap means with saidcontainer to apply pressure upon said first cap to further compress saidlayer of resilient sealing material to a desired second degree ofcompression.

2. A sealing closure as defined in claim 1, wherein said connectingmeans for connecting said overcap means with said container comprisesradially inwardly directed tear-away rim means (38) carried by the lowerextremity of said second skirt portion for engagement with acorresponding external annular shoulder on said container.

3. A sealing closure for the open end of a container having externalclosure retaining means, comprising:

a first cap adapted for mounting across the container opening;

a layer of resilient sealing material provided within said first cap forengaging and sealing the open end of said container;

a separation disc positioned between said layer of resilient sealingmaterial and said first cap;

internal engagement means carried by said first cap for engaging saidexternal closure retaining means to compress said resilient sealingmaterial to provide a light seal against the open end of said container,said internal engagement means being formed to permit limitedlongitudinal movement of said first cap relative to said closureretaining means after engagement therewith; and

overcap means adapted to overlie said first cap and to engage saidclosure retaining means to apply external pressure to said first cap ina direction to further compress said layer of resilient sealing materialand thereby provide increased sealing pressure against the open end ofsaid container.

4. The sealing closure of claim 3 wherein said separator disc andresilient layer constitute independent elements separate from said firstcap and unattached thereto.

5. A sealing closure for the open end of a container having externalscrew-thread closure retaining means formed thereon, comprising:

a first cap adapted for mounting across the container opening, saidfirst cap including internal screwthread engagement means for engagingsaid external closure retaining means, the teeth of said externalclosure retaining means being spaced to permit said internal threads tomove longitudinally therebetween, thereby affording limited longitudinalmovement of said first cap relative to said external closure retainingmeans after engagement therewith; and

overcap means adapted to overlie said first cap and to engage saidclosure retaining means, said overcap means operating when engaged withsaid closure retaining means to apply external pressure to displace saidfirst cap longitudinally against the open end of said container toincrease the sealing pressure thereof.

6. The sealing closure of claim 5 wherein said external closureretaining means includes a projecting bead formed below said externalthreads, said overcap having a depending fiange adapted to engage saidprojecting bead to hold said overcap against said first cap.

7. The sealing closure of claim 6 wherein a layer of resilient sealingmaterial is provided within said first cap for engaging and sealing theopen end of said container, a metallic separator disc is positionedbetween said layer of resilient sealing material and said first cap, andsaid overcap means is formed by a tearaway cap.

8. The sealing closure of claim 4 wherein said separator disc andresilient layer are formed to extend laterally beyond the confines ofthe open end of said container when said first cap engages said closureretaining means.

9. The sealing closure of claim 7 wherein said first cap includes aninwardly projecting retaining bead formed internally thereof and spacedfrom said internal threads to engage and retain said resilient sealingmaterial.

10. The sealing closure of claim 1 wherein said overcap means includesinwardly projecting contact surface means for engaging said first capwhen said overcap means is engaged with said closure retaining means,said contact surface means being formed to reduce the contact areabetween said overcap means and first cap.

11. The sealing closure of claim 5 wherein said overcap means includesinternal thread means for engaging said external threads on saidcontainer below the lower extremity of said first cap when said firstcap is in place on said container, said overcap means including inwardlyprojecting contact surface means for engaging said first cap, saidcontact surface means being formed to reduce the contact area betweensaid overcap means and first cap.

References Cited UNITED STATES PATENTS 3,158,282 11/1964 Housz 22029 X3,303,955 2/1967 Osborne et al 215-42 X GEORGE T. HALL, Primary ExaminerU.S. Cl. X.R.

